Geometry object size when exchanging of WKT/WKB encoded geometries.

Introduction The ordinates stored in an geometry objects, across all spatial data types do not have any rounding applied to their values. This is one aspect of data management that is seldom considered by most practitioners. Other articles in this website deal with how to round their values. This article is about a related topic”Read More

Geometry Validity and Method Access

Introduction All database spatial types that I have worked with have constructors based on Well Known Text (WKT). When constructing a geometry all those types check the WKT’s structure. So, for example, the polygon below is wrong for two reasons: 1. It does not have its exterior ring correctly defined (eg “POLYGON((…))” ; 2. ItRead More

CheckRadii: Identifying Tight Radius Curves sections within LineString geometry data

Sometimes it is a data quality requirement for linear data (roads, pipelines, transmission lines) that curves within the lines must have a radius greater than a particular amount. Recently a customer asked me to write some TSQL functions to help them run data quality checks over linear data loaded into a SQL Server 2008 geometryRead More

Oracle Spatial Mapping and Map Rendering Performance Tips

Comment: This article was written about 10 years ago. Most of what is written is still relevant though the comments about disk usage and access do not apply if SSD is being used. Introduction There are lots of things one can do to improve performance in mapping environments because of a lot of the visualisationRead More

The Frontage Problem: Creating references from land parcel street frontage boundary to point in street

This article demonstrates the power of database-based spatial processing. The business requirement is to determine, dynamically, the side of a land parcel that faces the street (could be single 2 point straight line to something more complex), and then determine the clockface direction from either ends of the frontage or the middle, to a object in the roads reserve (eg telecommunications pit).

STInsertN: Insert single vertex into a geometry

SQL Server Spatial, unlike spatial database type systems such as PostGIS, does not provide coordinate editing functions: STAddPoint STUpdatePoint STDeletePoint These functions are not a part of either the SQL or OGC standards. In fact neither provide an API for the SQL editing of geometry objects. If one wishes to do so, one must programRead More

STUpdateN: Update (replace) a single vertex within a geometry object.

SQL Server Spatial, unlike spatial database type systems such as PostGIS, does not provide coordinate editing functions: STAddPoint STUpdatePoint STDeletePoint These functions are not a part of either the SQL or OGC standards. In fact neither provide an API for the SQL editing of geometry objects. If one wishes to do so, one must programRead More